This invention relates to aqueous coating compositions and in particular to an aqueous dispersion of a polysulfone resin.
Industry requires finishes that are tough, durable and scratch resistant and are thermally stable for equipment subjected to heat such as household and industrial ovens. Bakeware and cookware require finishes that have food release properties and thermal stability. Also, the exterior areas of cookware such as fry pans, covers for fry pans, the sides and bottoms of electric cooking appliances require finishes that are tough, durable and thermally stable. Coating compositions that form these finishes should be non-airpolluting and preferably, therefore should be aqueous solutions or dispersions.
Finishes of polysulfone resins meet the requirements of toughness, durability, scratch resistance and thermal stability. These resins are well known in the art as shown by Vogel U.S. Pat. No. 3,321,449, issued May 23, 1967; British Pat. No. 1,122,192, published July 31, 1968; D'Alessandro U.S. Pat. No. 3,355,272, issued Nov. 28, 1967; Cohen et al. U.S. Pat. No. 3,518,235, issued June 30, 1970; Pietrusza et al. U.S. Pat. No. 3,536,665, issued Oct. 27, 1970. However, it has not been possible to formulate these resins into aqueous coating compositions.
The novel process of this invention prepares a non-airpolluting aqueous dispersion of aromatic polysulfone resins and these novel aqueous polysulfone dispersions form finishes that have excellent adhesion to all types of substrates and are tough, durable, scratch resistant and thermally stable and have excellent release properties.